<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            padding: 0;
            margin: 0;
        }

        .box {
            width: 200px;
            height: 200px;
            background-color: #6ff;
            margin: 50px;
            overflow: hidden;
        }

        .sub {
            width: 100px;
            height: 100px;
            background-color: pink;
            margin: 50px;

        }
    </style>
</head>

<body>
    <div class="box"></div>
</body>
<script>

    // 鼠标事件的事件对象 (onmouseover/onmouseout  onmouseenter/onmouseleave)
    // fromElement   事件触发时,从哪个元素来()
    // toElement     事件触发时,到哪个元素去()

    var box = document.getElementsByClassName("box")[0];

    box.onmouseover = function (e) {
        console.log("鼠标移入");
        console.log("从哪来", e.fromElement);
        console.log("到哪去", e.toElement);
    }

    box.onmouseout = function (e) {
        console.log("鼠标移出");
        console.log("从哪来", e.fromElement);
        console.log("到哪去", e.toElement);
    }

    // box.onmouseenter = function () {
    //     console.log("鼠标移入");
    // }

    // box.onmouseleave = function () {
    //     console.log("鼠标移出");
    // }







</script>

</html>